On printers which do not support duplexing, users have to resort to printing all
the odd pages of a document, putting those print outs back into the tray upside
down, and then printing all the even pages of a document.

However, gnome-print does not have an option to do this.  Each and every page
must be manually printed in order to get dual-sided printouts on printers
without native duplex support.

Being able to simply select "all odd pages" and "all even pages" in the
gnome-print dialog would alleviate this headache.